Microarray Analysis of Paramylon, Isolated from Euglena Gracilis EOD-1, and Its Effects on Lipid Metabolism in the Ileum and Liver in Diet-Induced Obese Mice.

Seiichiro Aoe,Kento Mio,Chiemi Yamanaka

doi:10.3390/nu13103406

Abstract

We previously showed that supplementation of a high fat diet with paramylon (PM) reduces the postprandial glucose rise, serum total and LDL cholesterol levels, and abdominal fat accumulation in mice. The purpose of this study was to explore the underlying mechanism of PM using microarray analysis. Male mice (C57BL/BL strain) were fed an experimental diet (50% fat energy) containing 5% PM isolated from Euglena gracilis EOD-1 for 12 weeks. After confirming that PM had an improving effect on lipid metabolism, we assessed ileal and hepatic mRNA expression using DNA microarray and subsequent analysis by gene ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. The results suggested that dietary supplementation with PM resulted in decreased abdominal fat accumulation and serum LDL cholesterol concentrations via suppression of the digestion and absorption pathway in the ileum and activation of the hepatic PPAR signaling pathway. Postprandial glucose rise was reduced in mice fed PM, whereas changes in the glucose metabolism pathway were not detected in GO classification and KEGG pathway analysis. PM intake might enhance serum secretory immunoglobulin A concentrations via promotion of the immunoglobulin production pathway in the ileum.

Highlights

Obesity and overweight are worldwide problems caused by lifestyle and genetic backgrounds [1]
We previously reported that PM had a beneficial effect in preventing obesity related parameters; in particular, abdominal fat accumulation and serum low-density lipoprotein (LDL) cholesterol levels
We confirmed that PM improved lipid metabolism in mice fed a high-fat diet, which was consistent with our previous report [20], before continuing with microarray analysis

Summary

Introduction

Obesity and overweight are worldwide problems caused by lifestyle and genetic backgrounds [1]. Chronic inflammation induces glucose intolerance, dyslipidemia, and an impaired immune defense system, which suggests that lifestyle changes, especially dietary habits, are very important. Dietary fiber is a beneficial food component, which is reported to improve obesity-related diseases [3]. Viscous or fermentable dietary fibers improve glucose intolerance [4], prevent body-weight gain [5], and improve dyslipidemia [6,7]. Beta-1,3-1,4-glucan is a typical viscous and fermentable dietary fiber found in cereals; it is reported to play a crucial role in the modification of obesity-related disorders. Barley β-glucan reduces the abdominal fat area [10] and improves glucose intolerance [11]. Beta-1,3-1,6-glucan, found in yeast and mushroom, is an almost insoluble dietary fiber, reported to enhance the immune response via dectin-1 [12]

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